Telephone-receiver.



A. PLEGHBR.

TELEPHONE RECEIVER. APPLICATION FILED MAR.29, 1913.

Patented Sept. 8,1914

3 SHEETS-SHEBT 1.

vi m

ewfleclber; INVENTOR,

VWITNESSES ATTORNEY A. PLEGHER.

TELEPHONE RECEIVER. APPLIGATION FILED MAR. 29, 1912.

v 1 1 0,228. Patented Sept. 8, 1914;

3 SHEETS-SHEET 2'.

\\ d ew/ im]; MEN

mg? Q WITNESSES ATTORN EY A. PLEUHER.

TELEPHONE RECEIVER.

APPLICATION TILED 111111.29. 1912.

Patented Sept.- 8,1914.

3 SHEETS-SHEET 3.

MW l 1 11: WITNESSES ATTORNEY l unrrun sTATEsggENT orrion.

ANDREW PLEGHER,. 0F LAS ANIIVIAS, COLORADQ.

; nurses.

TELEPHONE-RECEIVER.

tinuation of application Serial No. 608,298,.111e6 1912.

To all about it may concern: 7

Be it known that I, ANDREW PLnoin iR, a citizenof the United States,residing at Las Animas, in the county of Bent and State of Colorado,haveinvented a new and useful sensitivenesS .to electric impulses comingover the line thanarethe receivers ordig narily in use, while at th esame rimane. choking effect present in the ordinary-re; ceivers iseliminated. v j

In accordance with the present invention there is provided a receivingmagnet, prefer} ably of annular form in conjunctioii with receivingdiaphragm preferably supported by a circularly arranged" 'fulgruin intermediate of the innerand outer fportion of said diaphragm, withfthe1nagnet..elfective particularly adjacent to the periphery thereof.Moreover, the diaphragm acts on niicrophonic element and the magnetisprovided with a-coil having the microphonic element in: circuittherewith and both in operation are charged by a source of current v sothat line impulses act upon the' dia phragin through the eleetro magnetto set the diaphragm in vibration,.,and this vibration, causes acorresponding variation in resistance to the local circuit in, themicnophonic element, thereby highly aifecting the. current which setsupthe magnetism in-the receiving coil' to in turn act upon thediaphragm, the receiving-coil also acting in "conjunction with any othercoil in the circuits. ,The result of thisis that the incoming impulsesare reinforced and the d1aphragm 1S always, according to line 1mpulses,loudly and distinctly vibrated, which is not'the ease in receivers. 7

In the common commercial forms of tele phone receivers the diaphragm isclamped at the margin, and is otherwise superficially free, thereceiving magnet acting upon the central portion or the diaphragm. Suchdiaphragms are notoriously unresponsive to those overtones orcorresponding electrical impulses to which the quality of soundknown astimbre is due. In accordance with the ordinary commercialthepresentinvention the diaphragm is so 7 Specification of Letters Patent.

swarm. 687,066.

Patented Sept. 8, 1914.-

. 1 February 3, 1911. -This applieatimrfiled March 29,

from other sections, and these sections are J v sufficiently numerous topresent one or more sect onsfhavmg a natural rate of vibrationcorrespondlng to. an 'overtone to move with greater amplitude thanotherwise, for the reason tl iat it-vibrates in sympathy with .s ichover tonef The many diaphragm portions or segments providedpractically cover .therzirige of vibration of the speaking voiceinclusive of the fundamental rates and the rates of vibration of theovertones or harmonies. conjunction with the reactlng of-the dia..

Thechoking efiect of the coil in phragni armature and the muiiiing ofthe vibrations of-the diaphragm of the ordinary receiver due to thefaulty construction thereof is eliminated by the present invention wherethe diaphragm vibrates with markedly increased amplitude in response tothe received impulses to thereby repro-' duce I the transmitted soundnaturally, clearly and loudly.

1 The invention will be best understood from a consideration of thefollowing detailed description, taken in connection with theaccompanying drawings forming a part of this specification, with thefurther understanding that While the drawings show the 'invention inpart in practical form and in part diagrammatically,the invention issusceptible of other arrangements than those illustrated, wherefore itis not confined .to any strict conformity with the showing of thedrawings in its practical form, but may be .variously changed andmodified so long as such changes mark no material departure fromthe-salient features of the invention.

1 In the drawings :Figure 1 is a front elevation of the receiver. Fig. 2is a central section through the receiver ltaken from front to rear.Fig. 3 is a fragmentary section on the line 3-3 of Fig. 2. Fig. 4 is' aface viewof the diaphragm. Fig. 5 is a diagram of the circuitconnections. Fig. 6 is'a-sectional view of a modified form of thedevice, Fig. 7 is a sectional view of a modi- Fig. 8 is a face viewbfaportioniofwlthei. structure shown in Fig. 7. r

A In the practical embodiment ofthe inven tion the receiver may, so faras its external appearance is concerned, follow the linesof:

the ordinary telephone receiver, but for convenience. gof illustrationthe invention is shown as 'embo ied in a more compact form than" that ofthe ordinary receiver provided with an axial elongated hand-hold.

Referring moreparticularlyto the drawings'there is shown a body member 1of circular form, andwhich is usually made of hard rubber or somesimilar composition commonly employed in telephone instruments. The bodymember is formed with a mouth pieces of telephone receivers; Theinnerface ofthe cap member 4 is provided with an annular shoulder-6 designedto engage against-the body member 1 'and'to a small eXtent overlap thatportion of the chamber '2 diametrically enlarged to form throughout,Centrally in the spool 7 there is provided a cavity 14 for the receptionof a microphonic element 15, which latter may.

' tion. The showing of the drawings with rethe ledge 3/ Lodged 'n thechamber 2, is a spool 7 of appropriate material,v such as hard rubber orany suitable like composition, or any other 'non magneti'c materialappropriate for the purpose. 'The spool 7 is designed to receive a coil,indicated generally at 8, but which in fact comprises four coils 9, 10,11 and 12 with an intermediate core 13, which latter because of thecharacter. of the currents traversing the coils surrounding it may be ofa laminated nature, the word laminated being used in abroader sense asinclusive of either sheets, strips, rods or wires of magnetic material.The coil 8 may be conveniently formed by first winding upon the spool 7the coil 11, then upon the latter the coil 9, then placing the core 13upon the coil 9, which core may be wound upon the coil 9 when thecore isformedof iron-wire.

or bands or strips of iron. The coil 10 is then wound upon the core, andfinally the coil 12 is wound upon the coillO, it being understood thatdue insulation is provided he of the solid back transmitter type or anyother desired'type of microphonic element adaptedto the purposes ofthepresent invenspect to the microphonic element is more or lessschematic,'and as indicated, has a front plate 16, a back plate 17 andamass 1S ofi' g-ranules. Theback plate 17 is held in the cavity-14 by asuitable stud 19 and the jfront plate 16. carries a suitable stud 20:

The spool-7 is firmly lodged on the ledge w3311fitlueiieaxity 2'by theshoulder 6 of the cap4 engaging the spool close to the edge thereof,while the inner face of the cap 4 is suliicientl distantfrom the frontface of the spool when in placeto provide a cham ber 21; Fast to thespool 7 is a diaphragm 22 which may be somewhat heavier and "moreelastic than the diaphragms ordinarily in use, and this diaphragm isattached at the center to the front plate 16 of the microphonic elementby the stud 20 and appropriatefastening devices, such as are commonlyemployed in securing a diaphragm to a'microphonic element in thetelephone art and therefore need no particular. description. v Atpoints'between the cavity 1d and the outer edge of the diaphragm 22 thesaid diaphragm is-secured to the spool 7by screws with a ring 241',between the inner face of the diaphragm and the adjacent face of thespool 7 and another ring 25 on the outer face of the diaphragm, thescrews 23 clamping the diaphragm through the intermediary of the rings24 and 25.-

The diaphragm 22 is best shown in Fig. 4 and about its periphery thisdiaphragm has numerous inwardly directed slits 26 which in theparticular arrangement shown in the drawings are assembled in threegroups, each including an arc of about one hundred and twenty degrees,it being understood that the diaphragm is a circular disk and theseslits are longest at the intermediate portion ofthe arc and decrease inlength toward the ends of the arc, terminating approximately at thechord joining the ends of the arc. The three Zones of slits are producedabout a substantially equi-lateral triangular included portionl' of thediaphragm. The slits in the particular showing of Fig. 4 aresubstantially'r'adial to the to the endsthereof and may also'diminishtion is correspondingly increased.

An arrangement such as described is employed in practice, although thepractical form of the invent-ion need not follow with any partieularexactitude the showing of '23, or other appropriate fastening devicesvin width, so that their natural rate of. vibra-- respective apex ofthetriangle'opposite the shorter from the central portion of the arcFig. 4, if thetonguesor reedsindicatedl some distant transmitting pointa"The cells at 27 are properly tuned to be sensitive each to apredetermined rate of vibration so that when complex electrical impulsessuch as are caused by transmitted speech produce magnetic fluctuationsin operative relation to the diaphragm 22, which, of

course, is of magnetic material, some one or more-of the tongues 27 Wlllenergetically respond each to some one of the impulse components, thusgreatly reinforcing theefiec't of each and every rate of vibrationwithin the range of the tongues 27. These vibrating tongues set the airwithin the chamber 21 into vibration by lever action on the centralsolid portion and the air waves thus produced pass, out through theopening 5 to the ear of the listener. Since the diaphragm has portionsparticularly sensitive not only to the' lower tones or fundamentals ofthe transmitted speech waves in the form of electrical ulses, but to asutlic'iently great number 0 the harmonies or overtones, the latter aregreatly stren thened instead of being in part or wholl y obliterated andthe reproduced sound reaching the ear of the listener is sensiblyfaithful to the originally uttered sound at the distant transmitter.

It is to be further observed from the showingof Fig. 4 that the screwsor fastening devices 23 for the diaphragm are likewise disposed onehundred and twenty degrees apart and each is located in a perpendicularbise'ctor extending from a cor-.'

- responding vertex of the triangular section of the diaphragm to thebaseopposite such .vertex, such perpendicular bisectorpassing throu hthe center pin or stud 20 securing tral portion of the diaphragm} wherethe .microphonic element. I vices 23 have each a practically solidsupthe diaphragm to the front plate of the port in the spool 7 so thatvibrations imparted to the outer portion of the dia phragm which isthere free from any support whatsoever are tra-nsmitted'to the'cenlatteris connected'to the microphonic element, as though by a multitude oflevers havin their fulcrums in the rings'2i and 25. he central portionof the diaphragm not only acts as a solid diaphragm to set the air invibration in accordance with the vibrations of the active tongue ortongues, but the microphonic element is correspondingly agitated toproduce variations of resistance in the 'circuit controlled thereby andthe pulsating current thereby caused reacts through the coils 9 and 10to produce magnetic impulses in turn acting upon the dia-- 'phragm toamplify its vibrations initially produced by the incoming line impulses.

The circuit connections are best shown in Fig. 6. The line conductorsare indicated at 28-, 29, and are assumed to come from The fasteningdereceiver, so that so far as the microphonic element is concerned it isconnected up in series with the windings 9 and 10 in a local circuitincluding the local source of current, wherefore the circuit may forconvenicnce of'description be considered as a local circuit. Thewindings l] and 12 are connected up in series with the line con ductors28 and 29, and the combined winding may, therefore, be termed the linewindmg or coil. Included in the local circuit is a primary winding 3141fan induction coil such as is commonly used in telephone in-'stallations, and this induction coil has a secondary winding 32connected by conductors 33 to-the respectite-line wires 28 and 29 inmultiple with the combined windings 11 and 12. While the microphonicelement-with the diaphragm connected thereto has an important functionin connection with the instrument as a receiver it may also be-utiliz-ed as a transmitter, in which case the induction coil having thewindings 31 and 32 comes into service in the usual way. It will beunderstood, of course, that the usual cutting out switches employed intelephone installations are used in connection with the presentinvention, but have not been shown, since they form no part of thisinvention. The receiver is provided with a hook 34 by means of which itmay be suspended from the ordinary telephone hook or like device cuttingout the receiver or. local battery when the receiver is not inv use andis hung up. I

The annular receiver coil comprising the windings 11 and 12 is combinedwith the local coil made up of the windings 9 and 10, and these twocoils constitute an induction coil for which the microphonic ,elementoperates in'some degree like a circuit breaker for the inductionfloil.-It isdue to the fact that fewer turns are necessary in the receivermagnet of the present invention than in the receiver magnets of ordinaryreceivers and to th'e'construction of the diaphragm and the closerelation 'of the local and secondary windings of the receiver coil thatthe choc-king effect prominent in ordinary receivers is so markedlyeliminated in I the present device. 4 The microphonic element in thelocal battery circuit in series with the local magnetic winding producesa state of unstable equilibrium so that the incoming line impulses canm'ostlreadily modify the local current and thereby the magnetic effectacting on the diaphragm wheneforethe dia phragm is not only-moreforcibly attracted but is promptly released after; having been attractedand tea greaterextent as though a kick had beenimpartfld t0 thediaphragm Q-The multi-resonantdiaphragm should, for

the .best resultsgbe ,made 111 accordance with strict and-well known.principles of acoustics, so that the .tongues ;or segments vibrate inaccordance with the componentsof sound or harmonics. However, .even ifthey are approximately correct the tongues are more readily impressed byforced vibrations than are, diaphragins as ordinarily constructed,andthe improved diaphragm will give better results on the ordinary telephone than the diaphragm commonly in use. The marginal portion of thediaphragm is Wholly free to vibrate under magnetic influences, while thecomponents of they transmitted sounds are received individually andcompounded in the reproduction into a component sound, or if not comverage and magnetic pull, thus markedly.

- 'ent known Ways.

pounded, left a simple sound, just asthe case may be, this being broughtabout by the simultaneous vibrations of parts or segments in tune orapproximately in. tune with the transmitted impulses, whereby both thefundamentals and overtones of the sounds are augmented and reach the earof the listener.

Long experience has. demonstrated that the diameter of the receiverdiaphragm. of.

the commercial types of receiverscannot be increased without a seriousdiminishing of .the efiiciency, and, furthermore, expe'ence has taughtthat the magnets in use in ordi nary commercial telephone? receivers,since they are permanently magnetic,,cannot be regulated, controlled ortuned in-any way.

Thepresent invention has the advantage .over the ordinary commercialreceiver in that the diaphragm may be quite largely increased indiameterwith an increased leimproving the efiiciency. Moreover, in theIGCGlVBIDf thepresentinvention the magnetism is under. absolute controland can, therefore, be regulated and tuned in differarrangement acontinuous series of pinsor sta gl sv 35 project laterally'from a ring36, ,the pins and ring being made of soft iron,

and these pins project through suitable openings 37 a disk 38 which may"repre-. sent ahead r end of the spool 7. In this case the magnetic coremay be in the form of a wire winding 39- zlnterwoven about the pins 35or simply woundabout a series of pins as a support.

For some purposes the invention is operaable with otherfarrangements forlocally producing magnetic conditions active to the diaphragm andresponsive to the variable impulses transmitted over the main line.

Practice has demonstrated that the receiver coil is more efiective thanreceiver coils as ordinarily constructed, because of the greater amountof wire exposed to induction, there being in the annular coil an innersecondary and an inner primary, to-

together with an outer secondary and an outer primary.

When the instrument is used as a transmitter the receiver winding coactswith the secondary of the induction coil, but when the arrangement isused as a receiver the exterior induction coilwhen of the ordinary typewill act as a choke coil forcing. the

line current through the receiver coil and the local current will thenmerely maintain permanentmagnetism in the locally charged coil, whichmagnetism is, of course, modified by the line current.

The receiver herein described is particularly adapted for tuning to thevoice or instrument and also part to part, acoustically, electricallyand magnetically, wherefore it becomes possible with the receiver hereindescribed to tune the whole telephone circuit and all parts thereof inwhich the receiver is installed, thus permitting the utilization of allthe energy of the circuit harmoniously. j

The microplionic element acts in a manner similar to the detector orcoherer in wireless systems. When the line impulses induce a current 1nthe local microphone circuit of the receiver, and the current so inducedfiows in the-same. direction as the local-unidirectional current, then,and then only, such induced: current bridges. the microphcnicelement'and carries the local direct current with it through the microphonic element, whereas when the line impulses induce a current in thecontrary di motion to the local unidirectional current then suchcontrary induced current is.

checked and neutralized bythe local direct current. The result of thisaction is that the diaphragm is loudly and distinctly vibrated inaccordance with the line impulses in contradistinction to the action ofthe ordinary commercial receivers.

The invention is adapted for use as a relay or repeater. EQITJlhlSpurpose two reer-maze 1. A telephone-receiver provided with a diaphragmhavingcentral and marginal vibratory portions with a support betweensaid central and 'marginal portions and with the marginal? portion'yvholly free, and a magnet in inductive relation t'othe marginal freeportionpf the diaphragm! 2. A telephcfie receiver provided with adiaphragm having central and marginal vibratory sa-none; with a supportbetweensaid centr fafid marginal portions 'an'dwith the marginaltphrtion"wholly free, anda magnet in inductive relation to the mar glnalfree pe'rtibn" of 'the diaphragm, said magnet being of annular form andcon' structed' to earth the diaphragm adj ace'nt V the peripherythereof.

3x111 a receiver, a diaphragm provided with a siipport' between thecentral' and marginal porti ns; and having its marginal. portions 'fre'eto "vibrate, an--electro-magnet in inductlverela'tion to the freemarginal ,portio'ns of'fthediaphragm, circuit controlmg means connectedto the central portion of the diaphragm' and adapted to bein-' cludedinalocal charged circuit, and a coil included in circuit with thecircuitjcontrolling means and located in inductive relation to thephragm. v a

4. A telephone receiver. provided with a diaphragm having a microphonicelement connected to the central portion of the diaphragm with themarginal portions of the diaphragm wholly free to vibrate, and aninduction coil in inductive relation to the vInarginal, freely vibratoryportionsof the diaphragm with one winding adapted to be connected to aline circuit and the other winding included in the circuit with themicrophonic element and adapted to be connected up to a local chargedcircuit.

In a telephone receiver, a diaphragm provided with peripheral tonguestuned to respond to different rates of vibration, and a magnet ininductive relation to said tongues;- a

6. In a telephone receiver, a diaphragm having marginally locatedfreelyf vibratory tongues having difierent natural rates of magnetcontrolling the diavibration, and amagnet in inductive relation to saidtongues; v

, 7; In an acoustical instrument, a circular diaphragm provided withperipherally located, freelyvibratory tongues in zones with the tonguesof each zone: each having a natural rate of *fvibrati'oii differing fromothe'iisl'in said Zon,Kand"a -magnet in inductiverelat'ionto saidtongues.

8. In an*acoustical'instrumenfi a circular diaphragm having zones offreely vibratory tongues efitendin'g from an inner portion of thediaphragmflto tlieinargin thereof, and of diierent lengths the widthsand having cbrre'spondingly different natural rates of vibration, andelectromagnetic means in inductive relation to' said tongues.

"*9, "In anfac oustica'l nstrument, a clrcular diaphragm havingsubstantially segmental zones of l freely vibratory tongues havingtheir'f'ree ends at the periphery of the diaphragm, said zonesdescribing in the central portion of the diaphragm a substantiallyregular", geometric figure wherein the dia- Y ph ragmfis solid orunbroken by tongues, the

thiruesi'n a zone having each individually di iiere'nt natural rates ofvibration from others in the same zone, and electro-mag' netic means ininductive relation to said tongues. L i i Q 10. In telephone receiver, adia hragm Having its marginal portion wholly ree and unsupported, acentrally located circuit controlling meansconnected to the diaphragm, asupport for the diaphragm between the centrally located circuitcontrolling means and thefree periphery "of the diaphragm,

and an induction coil in inductive relation to the free marginalportions of the d1aphragm, said induction coil having a winding adaptedto be connected to line, and another winding connected to the circuitcon troller.

11. In a' telephone receiver, a circular dia- I phragm provided with aseries of peripheral tongues of varying length and varying width, meansfor supporting the diaphragm interior to the tongues,jand a magnetdisposed ne'ar the periphery of'the diaphragm for acting on saidtongues.

12; In a telephone receiver,.a circular diaphragm provided with a seriesof peripheral tongues of varying length and of varying width, a magnetdisposed near the periphery of the diaphragm for acting on said tongues,said magnet comprising a soft iron core, and a pair of separate windingsin in-' .ductive relation, and means for supplying current to each ofsald windings.

13. Ina telephone system, a receiver provided with a c'i'rculardiaphragm'having a series of peripheral tongues of varying length and ofvarying width, means for ,supportingthe central portion of thediaphragm, a magnet disposed near the periphcry of the diaphragm. foracting on said core a pair of separate windingson said e re and locatedadjacent the peripheryof t e diaphragm, a line circuitconnected with oneof said windings, and a local circuit including the transmitter andconnected with the other'of said windings.

. 15. In a telephone 'system, a telephone receiver, -.a casing providedwith a recess, a spool arranged to enter the recess in said casing, and111 turn provided with a central the windings of the magnet.

, eqess, a microphonic transmitter disposed the central recess of thespool, an annular soft, iron core carried by said spool,-two independentsetsof windings about said core, one, of said windings being'connectedwith the-transmitter, a local circuit connected to the lastnamed'winding, a line circuit connected to the other winding, and adiaphragm supported near its central portion and connected with thetransmitter, the periphery of the diaphragm being adjacent 16.- In atelephone system, a telephone receiver, a-casing provided with a recess,a spool arranged to enter the recess in the casing and in turn providedwith,a central recess, a microphonic transmitter disposedin thecentralrecess of the spool, an annular soft iron core-carried by thespool; two independent sets of windings about said core,

one of said windings being connected with the transmitter, a localcircuit connected to thelast named winding, a line" circuit connected tothe other winding, a diaphragm supported near its central portion andconnected with thetransmitter, the periphery ofthe diaphragm beingadjacent the wind ings of themagnet, and a screw cap for the casingadapted to hold thejspool-ainplace and provided with a recess arrangedto receive the diaphragm.

17. In a telephone system, a telephone receiver, a casing provided-witha recess, a

spool arranged to enter the recess in the casing and inturn providedwith a central recess, a microphonicv tIiLIlSIIllttGI: d sposed in thecentral recess of the spool, an annular soft iron core carried by saidspool, two in- 1 dependent sets of windings about said core,

one of said windings beingconnected with the'gtransmi'tter, a localcircuit connected to the-last named winding and the transmitter andincluding a battery, a linecircuit con nected to the other winding ofthe. magnet,

an induction c'oil having one winding in parallel with the line windingand the other winding included in the local'circuit, and a diaphragmsupported near its central portion and connected with said transmitter,the periphery of the diaphragm being adjacent the windings of themagnet.

18. In an acoustical instrument, a diaphragm supported between itsmarginal spaced from the center of the diaphragm to provide vibratoryportions both interior and exterior to the support and the exterior ormarginal portions of the diaphragm being wholly free, and a magnet inoperative relation to the free marginal portion of the diaphragm. 1

19. In an acoustical instrument, a diaphragm supported between itsmarginal and central. portions with said support spaced from the centerof the diaphragm to provide vibratory portions both interior andexterior to the support and the exterior or marginal portions of thediaphragm being wholly free. and ,a magnet in operative relation to thefree marginal portion of the diaphragm, said magnet comprising anannular core and a winding therefor.

20. In an acoustical instrument, a diaphragm having a wholly freemarginal portion andsupported interior to such free por- :tion' at adistance from the center of the diaphragm 'to provide a vibratoryportion of the diaphragm between its center and the support, and amagnet having a core and of'the diaphragm and in inductive relation. tothe free-marginal portion of said diaphragm.

21., In an acoustical instrument, a diaphragm having the marginalportion wholly free and locally tuned to respond to different chosen'rates of vibration, and 'electro- -magnetic means in osition withrespect to the said tuned portion of the diaphragmto act inductivelythereon. v

22-. In an acoustical instrument, a circular diaphragm having itsmarginal portions cally tuned to respond to different rates ofvibration, and electro-magnetic actuating means local to said tunedmarginal portions.

23. An I acoustical instrument having a diaphragm with its marginalportions in a plurality of zones locally tuned to respond todifi'erentrates of vibration, and"electromagnetic actuating means local to saidtuned marginal portion.

24. An acoustical instrument having av diaphragm of circular form withconnected segmental zones of the marginal portion slit from theperiphery toward the central porsided triangular portion unentered bythe slits, each series of slits being arranged sub stantially radialtothe apex of the triangle and central portions with said support windingexterior to the supported portion tion to extents defining asubstantially equiremote from the slits, and electro-magnetic actuatingmeans local to the slit marginal portion of the diaphragm.

25. An acoustical instrument having a diaphragm of circular form withconnected segmental zones of the marginal portion slit from theperiphery toward th" central portion to extents defining a substa ia-llyequilateral triangular portion unentered by the slits, each series ofslits being arranged substantially radial to the apex of the triangleremote from the slits, and said diaphragm being provided with supportingmeans e'ngaging the diaphragm in the unslit portion, andelectro-magnetic actuatin means local to the slit portions of the diapra m. a

26. An acoustical instrument aving a diaphragmof circular form withconnected segmental zones o f'the marginal p'ortion slit from theperiphery toward .the central portion to extents definingfasubstantiallyequilateral triangular portion unentered by the slits, each series ofslits being arranged substantially radial to the apex of the triangleremote from the slits, andsaid diaphragm-- being provided withsupporting means engaging the diaphragm in the unslit Portion, saidsupporting means being arranged to pierce-the diaphragm in substantiallythe lines of the perpendicular bisectors of the triangle, ande'lectro-magnetic means local to the slit portion of the diaphragm.

27. An acoustical instrument" provided with a plurality -of I vibratoryparts each movable about... an intermedlate support,

electro-magnetic'means in inductiverela-tion to one end of eachvibratory art, and means actively connected to the ot er endof thevibratory partsand responsive to vibrations imparted thereto" to augmentthe inductive *efi'ect of the electro-magnetic means upon said vibratoryparts.

28. An acoustical instrument. provided with a plurality of vibratoryparts each movable about an intermediate support,

.elec'troemagnetic means in inductive relation to one end of eachvibratory. art, and means actively connected to the ot er end of thevibratory parts and responsive to vibrations imparted thereto to augmentthe inductive eifect of the electro-magnetie-means upon said vibratoryparts, the' vibrator parts at the ends in'inductive relation to t eelectroma netic means being tuned toirespcnd to 'di erent'raltejs ofvibration.

QSI-A-tclerihone receiver hav' ,aldiaphragm for-;translating electricun.ulations transmitted over the line into sounds, means free frompermanent magnetism and controlled by the diaphragm for maintaining anelectro-magnetic field in operative relation to the diaphragmindependent of the telephone line currents and constituting the solemagnetic field of the receiver, and means for causing modifications ofsuch electromagnetic field by and in accordance with the telephone linecurrents.

30. A telephone receiver naving a diaphragm for translating'electricundulations transmitted over the line into sounds, means free frompermanent magnetism and controlled by the diaphragm for maintaining anelectromagnetic field in operative relation to the diaphragm independentof the telephone line currents and constituting the sole magnetic fieldof the receiver, and means for causing modifications of suchelectromagnetic field byand in accordance with the telephone linecurrents, means being in inductive relation to the means for producingthe magnetic field and the last-named I both of said means being locatedin a zone intermediate of the central and perlpheral portions of thediaphragm. Y

phragm and an inductlo'n coilin inductive relation thereto, one'windingof the coil beingadapted for energization by direct current, and-theother'winding being adapted to receive telephonic line currents, and amicrophcnic velement in: operative relation to the diaphragm on the sameside thereof as and connected to the winding energized by directcurrent, the microphonic element being, located in operative relation tothe central portion of the diaphragm, and the 1nduction coil being inoperative relation to an outer portion of the diaphragm and saiddiaphragm having supporting means located between the induction. coiland the micro.-

phonic element. v

In testimony, that I claim the foregoing as my own, I have heretoafiixed my signature in the presence of two witnesses.

' ANDREW PLECHER.

Witnesses".

- H. FREY,

P. G. Soo'rr.

